Nero 7 Premium HP 840d DVD Writer and can't get anything to disc!!

I've tried burning .iso, music files, DVDs...and it acts as if its performed the task. But then there appears to be nothing actually written to the disc. When I put the disc in the DVDROM drive and nagivate to it through My Computer I get a message instructing me to insert a disc into the drive. I don't even get the pop up window asking me what to do with the disc. I've uninstalled the DVD writer, reinstalled, looked for updated drivers. I've uninstalled and cleaned Nero off of my harddrive and reinstalled. I used to be able to burn. I can't figure it out. Help...please help.

Here you have installed Nero version 7.0.0.0 (which is a "buggy" version) over Nero6....first you have to remove Nero6 and get rid of 7.0.0.0...so do the following, Uninstall Nero7 and then run BOTH these clean tools Save your serial #

I have done everything suggested. Although I believe the Nero version I installed was 7.08 instead of 7.10. I am getting the same results. I click on my .iso file, Nero opens finds the burner. I burn the .iso, Nero says its complete and ejects the disc. I re-insert the disc into the DVD writer and it appears blank. I insert it into the DVD reader and its not even recognized. The CD-RW is Memorex and I took one of them that's been through this "process" to work where I was able to use Windows Media to burn .cda files to the disc. I can't figure out what's going on with my home system. Here's the new log: